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October 14, 2005

Mom’s ulcer bug may up leukemia risk in offspring

by Sam Savage

By Will Boggs, MD

NEW YORK (Reuters Health) - A study for the first time
hints that maternal infection with Helicobacter pylori -- the
bacterium that causes most cases of stomach ulcers -- is
associated with an increased risk of childhood leukemia in the
offspring.

Leukemia makes up 25 percent of all childhood cancers
worldwide and so-called acute lymphoblastic leukemia (ALL), the
most common form of the blood cancer, comprises about 80
percent of all childhood leukemias.

The fact that ALL tends to cluster in families and with
"population mixing" suggests ties between infection and
childhood leukemia, Dr. Matti Lehtinen from National Public
Health Institute in Oulu, Finland and colleagues explain the
American Journal of Epidemiology this month.

Lehtinen and colleagues used a cohort of 550,000 mothers
and their offspring to study the role of H. pylori as well as
two other common bacterial pathogens -- Mycoplasma pneumoniae
and Chlamydia pneumoniae -- in childhood leukemia. The subjects
resided in Finland or Iceland.

Taken in isolation, neither M. pneumoniae nor Chlamydia was
associated with an increased risk of childhood leukemia, the
report indicates.

In contrast, the authors report, in the group from Iceland,
having a mother test positive for H. pylori was associated with
a 2.8-fold increased risk of childhood leukemia in the
offspring. The risk was even higher (3.7-fold) when the
analysis was restricted to Icelandic cases diagnosed before the
age of 6 years, the results indicate.

In the group from Finland, however, H. pylori positivity
was not associated with an increased childhood leukemia risk,
the researchers note.

"To our knowledge," the authors conclude, "we have
documented for the first time the possibility of an association
between maternal H. pylori infection and risk of childhood
leukemia in the offspring. Independent confirmatory studies are
needed."